The objective of the project is to continue the development and evaluation of a radioisotope scintigraphic method of demonstrating the presence of intravascular inflammation and thrombosis based on the uptake of radiotracer particles (e.g., macroaggregates of albumin) on fibrin. The program has five basic parts: A. The basic investigation of elaborating the mechanism of localization of small radiolabeled particles on fibrin. B. Evaluation of other radioactive agents, including particles, which might better localize in areas of thrombosis. C. Clinical studies to evaluate the method; demonstration of the presence of thrombosis after elective surgery before symptoms or signs develop. These studies are to be correlated with tagged fibrinogen uptake, pulmonary scanning, and angiography studies. D. Studies using the technique as a tool for the evaluation of the effect on vascular endothelium of intravenous catheters and the effect of intravenously injected drugs (e.g., hyperalimentation solutions). E. The use of the method in evaluation of transplant organ preservation techniques. Deposition of fibrin as a result of endothelial change is now one of the major obstacles to successful preservation. This method offers a means of evaluating the extent of such endothelial damage.